This invention relates to a method of discerning esters of carbohydrates. More specifically, the present invention relates to a laboratory method that can be used to discern whether a carbohydrate ester is phosphorylated or sulfated.
When an isolated carbohydrate ester is analyzed using mass spectrometry there is no qualitative way to discern between a phosphate substitution and a sulfate substitution using mass spectrometry. This problem is due to the phosphate and sulfate esters being isobaric in a mass spectrometer.
The inability to discern between phosphate and sulfate substitution has hindered structural analysis of milk oligosaccharides. This in turn has limited the understanding of possible milk oligosaccharide's anti-cancer activities.
Using a hydride insertion reduction reaction a single hydrogen is added if a phosphate is present, thereby adding 1 amu. If a sulfate is present two hydrogens are added, thereby adding 2 amu. Since phosphorous and sulfur have 1 amu difference in atomic mass, the ions have 2 amu difference in molecular mass. This difference in molecular mass is sufficient for detection by mass spectrometers.
Thus, a principal object of the present invention is to provide a method for discerning between phosphate and sulfate substitution.